321H Stainless Steel Composition & High‑Temperature Strength

321H (UNS S32109) is the high‑carbon, titanium‑stabilized variant of 321 stainless steel. With 17–19% chromium, 9–13% nickel, and titanium added to prevent carbide precipitation, it offers improved resistance to sensitization during high‑temperature service. The increased carbon content (0.04–0.10%) significantly enhances creep strength and long‑term stability. 321H performs reliably between 600–850°C, making it suitable for boiler components, heat exchangers, exhaust systems, furnace structures, and high‑temperature pressure equipment. It maintains good weldability and does not require post‑weld heat treatment. 321H is supplied as sheets, plates, tubes, bars, and strips. As a strengthened version of 321, it provides superior high‑temperature performance for petrochemical, thermal‑processing, and aerospace applications.